Stubbornly high pregnancy prevalence in adolescent females worldwide, results in numerous adverse pregnancy outcomes, causing wide public concern. Thereby, it is pressing to study the pregnancy characteristics, adverse pregnancy outcomes and associated factors in adolescent primiparous females.

To examine adverse pregnancy outcomes and related factors in adolescent primiparous females via comparing pregnancy outcomes of them with those of emerging and early adult females.

Primiparous females (n=12 222, <35 year old) with ≥28 weeks of gestation were recruited from Ningbo Women and Children's Hospital during 2019—2020, including 210 aged 13-19 (adolescent group) , 1 729 aged 20-24 (adult group 1) , and 10 283 aged 25-34 (adult group 2) . Data were collected for maternal demographics, pregnancy complications, comorbidities, delivery course and adverse fetal outcomes. The associations of age, marital status, education background, rural or urban living, income, body mass index (BMI) with adverse maternal and fetal outcomes were analyzed.

Adolescent primiparas had higher proportions of individuals with unmarried status, junior high school or lower education level, rural living, and an unstable income, as well as less mean prenatal care visits than the other two groups (P<0.05) . Moreover, adolescent primiparas also had higher rates of placental abruption, maternal anemia, vaginal delivery, perineal laceration, premature labor, (very) low-birth-weight infant, and stillbirth (P<0.05) . Multivariate Logistic regression analysis demonstrated that in adolescent primiparas, 13-24 years, unmarried and BMI<18.5 kg/m² were associated with lower risk of gestational diabetes (P<0.05) ; gravida≥3 and BMI≥28 kg/m² were risk factors for gestational diabetes (P<0.05) ; 13-24 years, unmarried, unstable income and BMI≥28 kg/m² were risk factors for vaginitis (P<0.05) ; 13-19 year-old, unmarried, junior high school or lower education level and unstable income were risk factors for placental abruption (P<0.05) ; gravida≥3 was the risk factor for placenta previa (P<0.05) ; 13-24 years, unmarried, junior high school or lower education level, rural living and unstable income were risk factors for maternal anemia (P<0.05) ; BMI≥28.0 kg/m² was associated with lower risk of maternal anemia (P<0.05) . Further analysis showed that 13-24 years, unmarried, junior high school or lower education level, rural living and BMI<18.5 kg/m², were associated with higher possibility of having vaginal delivery (P<0.05) , whereas gravida≥3 was associated with higher possibility of having cesarean section (P<0.05) . Aged 13-19 years, unmarried, junior high school or lower education level, unstable income, gravida≥3, and BMI<18.5 kg/m² or ≥28.0 kg/m² were risk factors for premature labor (P<0.05) . Aged 13-19 year-old, unmarried, junior high school or lower education level, rural living, unstable income, gravida≥3, and BMI<18.5 kg/m² were risk factors for (very) low-birth-weight infants (P<0.05) . 20-24 year-old was associated with lower risk of fetal distress (P<0.05) . 13-19 year-old and unmarried were risk factors for stillbirth (P<0.05) . 13-24 years, junior high school or lower education level, rural living, unstable income, and gravida≥3 were risk factors for neonatal asphyxia (P<0.05) .

Adolescent primiparous females were featured by high rates of having unmarried status, rural living, an unstable income, low education level, fewer prenatal care visits, and adverse pregnancy outcomes. Younger age, unmarried, poor socioeconomic status, higher number of pregnancies, and excessive low or high BMI were risk factors for adverse pregnancy outcomes in this group. Healthcare specialists should schedule prenatal examinations for these people based on the high risk factors accordingly. And government at all levels and affiliated adolescent institutions should offer appropriate social and economic support for teenage mothers to reduce adverse pregnancy outcomes.

全球青少年妊娠率居高不下，造成较多不良后果，引起全社会的广泛关注，迫切需要对青少年初产妇的妊娠特点、不良妊娠结局及影响因素进行深入研究。

研究青少年初产妇和其他年龄段初产妇妊娠结局差异及相关影响因素。

分析2019—2020年宁波市妇女儿童医院产科<35岁的分娩孕周≥28周的12 222例初产妇及胎儿的妊娠结局，其中年龄≤19岁210例，设为青少年组；20~24岁1 729例，设为成人1组；25~34岁10 283例，设为成人2组。记录初产妇的一般情况、妊娠并发症、合并症、分娩情况及胎儿不良妊娠结局。分析年龄、婚姻、学历、居住地、经济状况、孕次、体质指数（BMI）对母婴不良妊娠结局的影响。

青少年组未婚、初中及以下学历、居住地为农村、无固定收入所占比例均高于成人1组和成人2组，产检次数少于成人1组和成人2组（P<0.05）。青少年组胎盘早剥、贫血、阴道分娩、会阴裂伤、早产、（极）低出生体质量儿、死胎发生率均高于成人1组和成人2组（P<0.05）。多因素Logistic回归分析结果显示，年龄≤24岁、未婚、BMI<18.5 kg/m²是初产妇发生妊娠期糖尿病的保护因素（P<0.05）；孕次≥3次、BMI≥28.0 kg/m²是初产妇发生妊娠期糖尿病的危险因素（P<0.05）；年龄≤24岁、未婚、无固定收入、BMI≥28.0 kg/m²是初产妇发生阴道炎的危险因素（P<0.05）；年龄≤19岁、未婚、初中及以下学历、无固定收入是初产妇发生胎盘早剥的危险因素（P<0.05）；孕次≥3次是初产妇发生前置胎盘的危险因素（P<0.05）；年龄≤24岁、未婚、初中及以下学历、居住地为农村、无固定收入是初产妇发生贫血的危险因素（P<0.05）；BMI≥28.0 kg/m²是初产妇发生贫血的保护因素（P<0.05）。多因素Logistic回归分析结果显示，年龄≤24岁、未婚、初中及以下学历、居住地为农村、BMI<18.5 kg/m²者更愿意选择阴道分娩（P<0.05），孕次≥3次者更愿意选择剖宫产（P<0.05）；年龄≤19岁、未婚、初中及以下学历、无固定收入、孕次≥3次、BMI<18.5 kg/m²、BMI≥28.0 kg/m²是早产儿发生的危险因素（P<0.05）；年龄≤19岁、未婚、初中及以下学历、居住地为农村、无固定收入、孕次≥3次、BMI<18.5 kg/m²是（极）低出生体质量儿发生的危险因素（P<0.05）；年龄20~24岁是胎儿窘迫发生的保护因素（P<0.05）；年龄≤19岁、未婚是死胎发生的危险因素（P<0.05）；年龄≤24岁、初中及以下学历、居住地为农村、无固定收入、孕次≥3次是新生儿窒息发生的危险因素（P<0.05）。

青少年初产妇呈现未婚、居住在农村及无固定收入所占比例高、受教育程度低、产检次数少、不良妊娠结局发生率高的特点。低龄、未婚、不良的社会因素和经济因素、多孕次、BMI过低或过高是青少年初产妇不良妊娠结局的影响因素。医疗保健专业人员应根据青少年高危因素制定适宜的围生期保健方案，政府及相应青少年服务机构应给予青少年母亲适当的社会经济支持，以降低不良妊娠结局的发生。